1. Field of the Invention
The present invention relates to a method for transmission of subscriber data, particularly the name and the subscriber connection number of a calling party, between a subscriber terminal equipment of a communication system, particularly a private branch exchange communication system, comprising a central controller, a central memory and subscriber equipment connected to the communication system and having a display for displaying the subscriber data, whereby an inhibit information that prevents the display of subscriber data at the called subscriber equipment is transmitted to a receiving communication system from defined, calling, secret subscriber equipmens in common with the subscriber data belonging to these subscriber equipment.
2. Description of the Prior Art
Many subscriber equipment of communication systems have a display available for displaying exchange-oriented data. Among other things, it is therefore possible for the user of such equipment to learn about the subscriber terminal from which a call comes on the basis of the display of the subscriber data of the calling party, even before accepting a call. The display of the subscriber data at the called party occurs, for example, in internal and external calls, in manual switching position traffic, in automatic call back, in call transfer, when changing the destination of a call (call forwarding, call rerouting), in connection personal paging equipment, etc. On the basis of this display, the called party can decide whether or not to accept the call on the basis of personal interest of specifically entering into a connection with the calling party.
This fact was a precondition for the requirement for what are referred to as secret subscriber equipment that prevent a transmission of the connection-related subscriber data to the desired called party. The integrated services digital network process (ISDN) perform its feature of "secret call number" takes this requirement into consideration. A corresponding inhibit information is deposited for each secret subscriber equipment in a memory of a communication system that offers this performance feature. When setting up an external connection, the called subscriber equipment being located outside the communication system of the calling subscriber, this inhibit information is transmitted up to the receiving communication system together with the telephone number and the subscriber name and is stored there. In an internal call setup, the inhibit information is already available and, as in the case of the external connection, effects that what is referred to as a dummy information that does not result in a display at the called party and is forwarded to the called subscriber equipment instead of the subscriber data. A calling party who has a subscriber equipment with the performance feature of secret call number therefore receives a permanent data protection. Due to this data protection, a rejection of the call by the called party is no longer possible on the basis of the knowledge of the subscriber data of the calling party. However, it is likewise no longer possible that, on the basis of the knowledge of the party data of the calling subscriber, a call is accepted with priority by the called party. For example, an urgently-expected "secret caller" can no longer be distinguished from undesired calling parties, for whatever reasons. Problems with respect to the acceptance of secret subscriber equipment thereby arise.